Antiretroviral therapy (ART) to treat HIV has changed the outlook of HIV infection, since well-managed patients can remain free of symptoms for long periods. However, chronic use of the drugs leads to toxicities and virus resistance. Therapy must be continued indefinitely, since HIV (or SIV in macaques) remaining in pharmacological sanctuaries, rebounds rapidly upon treatment interruption.
The administration of nucleic acid-based vaccines, including both naked DNA and viral-based vaccines, to individuals that have undergone ART has been suggested (see, e.g., WO01/08702, WO04/041997). Further, the administration of DNA vaccines in prime boost protocols has been suggested (see, e.g., US application no. 2004/033237; Hel et al., J. Immunol. 169:4778-4787, 2002; Barnett et al., AIDS Res. and Human Retroviruses Volume 14, Supplement 3, 1998, pp. S-299-S-309 and Girard et al., C R Acad. Sci III 322:959-966, 1999 for reviews).
DNA immunization followed by administration of another highly attenuated poxvirus has also been tested for the ability to elicit IgG responses, but the interpretation of the results is hampered by the fact that serial challenges were performed (see, e.g., Fuller et al., Vaccine 15:924-926, 1997; Barnett et al., supra). In contrast, in a murine model of malaria, DNA vaccination used in conjunction with a recombinant vaccinia virus was promising in protecting from malaria infection (see, e.g., Sedegah et al., Proc. Natl. Acad. Sci. USA 95:7648-7653, 1998; Schneider et al., Nat. Med. 4:397-402, 1998).
DNA immunization plasmids have been developed that encode fusion proteins that contain a destabilizing amino acid sequence attached to a polypeptide sequence of interest that when administered with a secreted fusion protein containing a secretory peptide attached to a polypeptide of interest enhances the immune response (see. e.g., WO02/36806). Combinations of such DNA immunization plasmids have been administered to animals that have undergone antiretroviral therapy (WO06/010106). The current invention provides further improvements to protocols for administering DNA vaccines to individuals who have received ART that result in improvements in immune responses to the target antigen(s).